Individual conjugates, were coupled with biotin and used for the

Individual conjugates, were coupled with biotin and used for the fluorescence enzyme immune assay detection method (semi-automatic ImmunoCAP100, Phadia, Freiburg, Germany). Serum-specific IgE is expressed in kilo unit per liter (kU/L) correlated with the WHO reference of human serum IgE (1 kU = 2.4 ng/mL). A seven-point dose–response calibration was performed for each IgE and IgG measurement. selleck products For ImmunoCAP-specific IgE, the limit of detection (LOD) of 0.02 kU/L for IgE and 0.2 mg/L for IgG and the limit of calibration of 100 kU/L for Commercial ImmunoCAP conjugates (K76, Phadia) used in routine clinical laboratories were applied in parallel with similar

analytical procedures (for the calibration curves and control sera). For validation of the assays, the following AZD8186 cell line controls were included: pooled positive and negative patient/control sera, analytical standards (also used as set points for quality control), HSA solution and biotin control samples. The measured day to day precision was <12 % RSD. The

assay validation was performed according to the good laboratory practice. Separate studies with HSA solution showed that IgE values above 0.02 kU/L and IgG values above 3 mg/L can be considered as specific (above means +2 RSD or 10 % analytical variation). The variability between the in-vapor method and the commercial assay method was: 0.5–20 %

(for lower and upper edge of failure) for the IgE values. For the IgG data, however, the values collected with commercial CAPs were continuously 5–35 % higher in all tested subjects. Total IgE antibodies were determined using respective commercial Uni-CAP from Phadia. Detection of MDI-bound to HSA The protein concentration of each test conjugate was determined by the method of Bradford (BioRad, Germany). The concentrations were adjusted by dilution or limited evaporation on a speed-vac system. The conjugates were subjected to SDS-PAGE using a 9 % separation gel. The amount of MDI-bound to HSA was calculated from the intact protein shift using MALDI-TOF-MS (using CHCA-matrix) and compared with this website non-conjugated HSA. LC-MS/MS measurements Purified HSA was incubated with MDI and analyzed by MALDI-TOF mass spectrometry (Applied Biosystems, the Netherlands) to determine the mass shift of the intact protein. Additionally, the reacted HSA was digested with trypsin (without any further treatments, such as disulfide bond reduction). The digested mixtures were analyzed by liquid chromatography (LC)-mass spectrometry (MS) (Applied Biosystems, the Netherlands), and modified peptides were scanned using neutral loss and precursor ion scans. Interesting ions were analyzed again with product ion scans to identify them from their fragmentation spectra (data not shown).

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